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  • A61K31/352—Heterocyclic compounds having oxygen as the only ring hetero atom, e.g. fungichromin having six-membered rings with one oxygen as the only ring hetero atom condensed with carbocyclic rings, e.g. methantheline 
  • A61K31/353—3,4-Dihydrobenzopyrans, e.g. chroman, catechin
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  • A61K31/352—Heterocyclic compounds having oxygen as the only ring hetero atom, e.g. fungichromin having six-membered rings with one oxygen as the only ring hetero atom condensed with carbocyclic rings, e.g. methantheline 
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  • A61K31/4025—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with one nitrogen as the only ring hetero atom, e.g. sulpiride, succinimide, tolmetin, buflomedil not condensed and containing further heterocyclic rings, e.g. cromakalim
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  • A61K31/41—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with two or more ring hetero atoms, at least one of which being nitrogen, e.g. tetrazole
  • A61K31/4164—1,3-Diazoles
  • A61K31/4178—1,3-Diazoles not condensed 1,3-diazoles and containing further heterocyclic rings, e.g. pilocarpine, nitrofurantoin
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  • A61K31/41—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with two or more ring hetero atoms, at least one of which being nitrogen, e.g. tetrazole
  • A61K31/42—Oxazoles
  • A61K31/422—Oxazoles not condensed and containing further heterocyclic rings
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  • A61K31/41—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with two or more ring hetero atoms, at least one of which being nitrogen, e.g. tetrazole
  • A61K31/425—Thiazoles
  • A61K31/427—Thiazoles not condensed and containing further heterocyclic rings
• • A—HUMAN NECESSITIES
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  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/435—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with one nitrogen as the only ring hetero atom
  • A61K31/44—Non condensed pyridines; Hydrogenated derivatives thereof
  • A61K31/445—Non condensed piperidines, e.g. piperocaine
  • A61K31/452—Piperidinium derivatives
• • A—HUMAN NECESSITIES
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  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/495—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with two or more nitrogen atoms as the only ring heteroatoms, e.g. piperazine or tetrazines
  • A61K31/496—Non-condensed piperazines containing further heterocyclic rings, e.g. rifampin, thiothixene
• • A—HUMAN NECESSITIES
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  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/535—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with at least one nitrogen and one oxygen as the ring hetero atoms, e.g. 1,2-oxazines
  • A61K31/5375—1,4-Oxazines, e.g. morpholine
  • A61K31/5377—1,4-Oxazines, e.g. morpholine not condensed and containing further heterocyclic rings, e.g. timolol
• • A—HUMAN NECESSITIES
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  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/54—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with at least one nitrogen and one sulfur as the ring hetero atoms, e.g. sulthiame
  • A61K31/541—Non-condensed thiazines containing further heterocyclic rings
• • A—HUMAN NECESSITIES
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  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/55—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having seven-membered rings, e.g. azelastine, pentylenetetrazole
• • A—HUMAN NECESSITIES
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  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P33/00—Antiparasitic agents
• • A—HUMAN NECESSITIES
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  • A61P33/00—Antiparasitic agents
  • A61P33/02—Antiprotozoals, e.g. for leishmaniasis, trichomoniasis, toxoplasmosis
  • A61P33/06—Antimalarials
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D493/00—Heterocyclic compounds containing oxygen atoms as the only ring hetero atoms in the condensed system
  • C07D493/12—Heterocyclic compounds containing oxygen atoms as the only ring hetero atoms in the condensed system in which the condensed system contains three hetero rings
  • C07D493/18—Bridged systems
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/30—Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change

Definitions

• This invention relates to the use of certain C-10 substituted derivatives of artemisinin in the treatment and/or prophylaxis of diseases caused by infection with a parasite, certain novel C-10 substituted derivatives of artemisinin, processes for their preparation and pharmaceutical compositions containing such C-10 substituted derivatives.
• Malaria is the most important human parasitic disease in the world today. Approximately 270 million people throughout the world are infected with malaria, with about 2 million dying each year. The ability of parasites to produce a complex survival mechanism by expressing variant antigens on the surface of infected erythrocytes makes it possible for the parasites to escape from the destructive action of the host immune response against these antigens. In addition, the increasing rate of malaria infection is due to the spread of chloroquine-resistant strains of Plasmodium falciparum and the other multi-drug resistant strains.
• Neospora infections are known to occur in dogs, cattle, sheep, goats and horses.
• Neospora spp. including Neospora caninum
• the final host for Neospora spp. is unknown and, in addition, the complete cycle of development of the parasite is not understood.
• the asexual phases of reproduction, known as schizogony, and the behaviour of the unicellular tachyzoite/bradyzoite stage have been clarified, however.
• Tachyzoites are infectious unicellular parasite stages of about 3-7 ⁇ 1-5 mm in size formed after intracellular reproduction termed endodyogeny. Reproduction via tachyzoites takes place preferentially in organelles such as muscle or nerve cells. Pathological symptoms invoked after an infection are associated mainly in those tissues.
• Neospora caninum infections appear to be the main cause for abortion in cattle. Symptoms of the disease in cattle are similar to those in the dog. Ataxia is apparent, joint reflexes are weakened and pareses at the hind legs, partly in all four legs, can be observed. The histological picture is similar to that of the dog; mainly non-suppurative meningitis and myelitis.
• Coccidiosis an infection of the small intestine, is relatively rarely diagnosed in humans, where it is caused by Isospora belli .
• humans are also the final host of at least two cyst-forming coccidial species ( Sarcocystis suihominis and S. bovihominis ). Consumption of raw or inadequately cooked pork or beef containing such cysts can lead to severe diarrhoea, the cause of which is probably seldom diagnosed correctly.
• Coccidia (phylum Apicomplexa, suborder Eimeriina) are one of the most successful groups of parasitic protozoans, having conquered virtually every class of Metazoa. The ones that are of particular importance for man are the 60-100 species which parasitise domestic animals and which in some instances can cause very severe losses, especially in poultry, although also in lambs, calves, piglets, rabbits and other animals (see Table A).
• prophylaxis is the main approach in poultry, in which symptoms do not appear until the phase of increased morbidity, and therapy is the principal strategy in mammals (McDougald 1982).
• Polyether antibiotics and sulfonamides, among other drug, are currently used for such treatment and prophylaxis.
• drug-resistant strains of Eimeria have emerged and drug-resistance is now a serious problem. New drugs are therefore urgently required.
• the compound artemisinin also known as qinghaosu (1), is a tetracyclic 1,2,4-trioxane occurring in Artemisia annua .
• Artemisinin and its derivatives dihydroartemisinin (2), artemether (3) and sodium artesunate (4) have been used for the treatment of malaria.
• the oxygen atom at C-10 can be either removed to provide 10-deoxydihydroartemisinin, or replaced by other groups, and this has provided the basis for the so-called ‘second generation’ compounds which are generally 10-deoxy artemisinin derivatives.
• derivatives of artemisinin have also been prepared with a variety of substituents at C-9.
• Artemisinin derivatives are also known in which the oxygen atom at C-10 has been replaced by an amine group.
• Yang et al (Biorg. Med. Chem. Lett., 1995, 5, 1791-1794) synthesised ten new artemisinin derivatives in which the oxygen atom at C-10 was replaced by a group —NHAr where Ar represents a phenyl, 3-chlorophenyl, 4-chlorophenyl, 3-bromophenyl, 4-bromophenyl, 4-iodophenyl, 4-methylphenyl, 4-methoxyphenyl, 3-carboxylphenyl or 4-carboxylphenyl group. These compounds were tested for in viva activity against the K173 strain of Plasmodium berohei and found to be active.
• Suitable salts include acid addition salts and these way be formed by reaction of a suitable compound of formula I with a suitable acid, such as an organic acid or a mineral acid. Acid addition salts formed by reaction with a mineral acid are particularly preferred, especially salts formed by reaction with hydrochloric or hydrobromic acid.
• Y represents a group —NR 1 R 2 where R 1 and R 2 are as defined above are particularly suitable for the formation of such acid addition salts.
• any alkyl, alkenyl or alkynyl group may be linear or branched and may contain up to 12, preferably up to 6, and especially up to 4 carbon atoms.
• Preferred alkyl groups are methyl, ethyl, propyl and butyl. It is preferred that any alkenyl or alkynyl group is not an alk-1-enyl or alk-1-ynyl group. In other words, there should preferably be at least one methylene group —CH 2 — or similar sp 3 -hybridised centre between a carbon atom forming part of the double or triple C—C bond and the nitrogen atom to which the group is attached.
• Preferred alkenyl and alkynyl groups include propenyl, butenyl, propynyl and butynyl groups.
• an alkyl moiety forms part of another group, for example the alkyl moiety of an aralkyl group it is preferred that it contains up to 6, especially up- to 4, carbon atoms.
• Preferred alkyl moieties are methyl and ethyl.
• An aryl group may be any aromatic hydrocarbon group and may contain from 6 to 24, preferably 6 to 18, more preferably 6 to 16, and especially 6 to 14, carbon atoms.
• Preferred aryl groups include phenyl, naphthyl, anthryl, phenanthryl and pyryl groups, especially a phenyl or napthyl, and particularly a phenyl, group.
• an aryl moiety forms part of another group, for example the aryl moiety of an aralkyl group, it is preferred that it is a phenyl, naphthyl, anthryl, phenanthryl or pyryl, especially phenyl or naphthyl, and particularly a phenyl, moiety.
• An aralkyl group may be any alkyl group substituted by an aryl group.
• a preferred aralkyl group contains from 7 to 30, particularly 7 to 24 and especially 7 to 18, carbon atoms, particularly preferred aralkyl groups being benzyl, naphthylmethyl, anthrylmethyl, phenanthrylmethyl and pyrylmethyl groups.
• a particularly preferred aralkyl group is a benzyl group.
• a cycloalkyl group may be any saturated cyclic hydrocarbon group and may contain in from 3 to 12, preferably 3 to 8, and especially 3 to 6, carbon atoms.
• Preferred cycloalkyl groups are cyclopropyl, cyclopentyl and cyclohexyl groups.
• a heteroaryl group may be any aromatic monocyclic or polycyclic ring system which contains at least one heteroatom.
• a heteroaryl group is a 5-18-membered, particularly a 5- to 14-membered, and especially a 5- to 10-membered, aromatic ring system containing at least one heteroatom selected from oxygen, sulphur and nitrogen atoms.
• Preferred heteroaryl groups include pyridyl, pyrylium, thiopyrylium, pyrrolyl, furyl, thienyl, indolinyl, isoindolinyl, indolizinyl, imidazolyl, pyridonyl, pyronyl, pyrimidinyl, pyrazinyl, oxazolyl, thiazolyl, purinyl, quinolinyl, isoquinolinyl, quinoxalinyl, pyridazinyl, benzofuranyl, benzoxazolyl and acridinyl groups.
• a C-linked heteroaryl group is therefore a heteroaryl group as defined above which is linked to the tetracyclic 1,2,4-trioxane moiety of a compound of general formula I via a carbon atom in the heteroaromatic ring system.
• a heterocyclic group may be any monocyclic or polycyclic ring system which contains at least one heteroatom and may be unsaturated or partially or fully saturated.
• the term “heterocyclic” thus includes heteroaryl groups as defined above as well as non-aromatic heterocyclic groups.
• a heterocyclic group is a 3- to 18-membered, particularly a 3- to 14-membered, especially a 5- to 10-membered, ring system containing at least one heteroatom selected from oxygen, sulphur and nitrogen atoms.
• Preferred heterocyclic groups include the specific heteroaryl groups named above as well as pyranyl, piperidinyl, pyrrolidinyl, dioxanyl, piperazinyl, morpholinyl, thiomorpholinyl morpholinosulphonyl, tetrahydroisoquinolinyl and tetrahydrofuranyl groups.
• a heterocyclylalkyl group may be any alkyl group substituted by a heterocyclic group.
• the heterocyclic moiety is a 3- to 18-membered, particularly a 3- to 14-membered, and especially a 5- to 10-membered, heterocyclic group as defined above and the alkyl moiety is a C 1-6 alkyl, preferably C 1-4 alkyl, and especially methyl, group.
• An amino acid may be any ⁇ -amino acid, such as glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, aspargine, glutamine, lysine, hydroxylysine, arginine, histidine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline or phenylglycine, and includes both D- and L-configurations.
• An amino acid ester may be any ester of such an amino acid, alkyl esters, particularly C 1-4 alkyl esters, being especially preferred.
• substituent groups which are optionally present may be any one or more of those customarily employed in the development of pharmaceutical compounds and/or the modification of such compounds to influence their structure/activity, stability, bioavailability or other property.
• substituents include, for example, halogen atoms, nitro, cyano hydroxyl, cycloalkyl, alkyl, alkenyl, haloalkyl, alkoxy, haloalkoxy, amino, alkylamino, dialkylamino, formyl, alkoxycarbonyl, carboxyl, alkanoyl, alkylthio, alkylsulphinyl, alkylsulphonyl, alkylsulphonato, arylsulphinyl, arylsulphonyl, arylsulphonato, carbamoyl, alkylamido, aryl, aralkyl, optionally substituted aryl, heterocyclic and alkyl- or aryl-substituted heterocyclic groups.
• substituents represents or contains an alkyl or alkenyl substituent group
• this may be linear or branched and may contain up to 12, preferably up to 6, and especially up to 4, carbon atoms.
• a cycloalkyl group may contain from 3 to 8, preferably from 3 to 6, carbon atoms.
• An aryl group or moiety may contain from 6 to 10 carbon atoms, phenyl groups being especially preferred.
• a heterocyclic group or moiety may be a 5- to 10-membered ring system as defined above.
• a halogen atom may be a fluorine, chlorine, bromine or iodine atom and any group which contains a halo moiety, such as a haloalkyl group, may thus contain any one or more of these halogen atoms.
• Y represents a halogen atom, particularly a fluorine or bromine, and especially a fluorine, atom.
• Y may represent a C 3-8 cycloalkyl group, a C 6-18 aryl group, a 5- to 10-membered C-linked heteroaryl group or a 5- to 10-membered heterocyclyl-C 1-6 alkyl group, each group being optionally substituted by one or more substituents selected from the croup consisting of halogen atoms, hydroxyl, C 1-4 alkyl, C 2-4 alkenyl, C 1-4 haloalkyl, C 1-4 alkoxy, amino, C 1-4 alkylamino, di(C 4 alkyl)amino, carboxyl, C 6-10 aryl, 5 to 10-membered heterocyclic and C 1-4 alkyl- or phenyl-substituted 5- to 10-membered heterocyclic groups.
• Y represents a C 6-18 aryl group optionally substituted by one or more substituents selected from the group consisting of halogen atoms, hydroxyl, C 1-4 alkyl, C 2-4 alkenyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, amino, C 1-4 alkylamino, di(C 1-4 alkyl)amino and carboxyl groups.
• Y may represent a phenyl, naphthyl, anthryl or phenanthryl group, each group being optionally substituted by one or more substituents selected from the group consisting of halogen atoms and hydroxyl, methyl, vinyl, C 1-4 alkoxy and carboxyl groups.
• Y represents a phenyl, fluorophenyl, chlorophenyl, bromophenyl, tri-ethylphenyl, vinylphenyl, methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, carboxylphenyl, naphthyl, hydroxynaphthyl, methoxynaphthyl, anthryl or phenanthryl group.
• Compounds in which Y represents a phenyl or trimethoxyphenyl group are especially preferred.
• Y may represent a group —NR 1 R 2 where R 1 represents a hydrogen atom or a C 1-6 alkyl group and R 2 represents a C 1-6 alkyl, C 3-4 cycloalkyl, C 6-10 aryl or C 7-16 aralkyl group, or R 1 and R 2 together with the interjacent nitrogen atom represent a 5- to 10-membered heterocyclic group or an amino group derived from a C 1-6 alkyl ester of an amino acid, each group being optionally substituted by one or more substituents selected from the group consisting of halogen atoms, C 1-4 alkyl, C 1-4 haloalkyl, C 1-6 alkoxycarbonyl, phenyl, halophenyl, C 3-4 alkylphenyl, C 1-4 haloalkylphenyl, C 1-4 alkoxyphenyl, benzyl, pyridyl and pyrimidinyl groups.
• R 1 represents a hydrogen atom or
• Y may represent a group —NR 1 R 2 where R 1 represents a hydrogen atom or a C 1-4 alkyl group and R 2 represents a C 1-4 alkyl, C 3-6 cycloalkyl, phenyl or benzyl group, or R 1 and R 2 together with the interjacent nitrogen atom represent a 6- to 10-membered heterocyclic group or an amino group derived from a C 1-4 alkyl ester of an amino acid, each group being optionally substituted by one or more substituents selected from the group consisting of halogen atoms, C 1-4 haloalkyl, C 1-4 alkoxycarbonyl, phenyl, halophenyl, C 1-4 alkylphenyl, C 1-4 haloalkylphenyl, C 1-4 alkoxyphenyl, benzyl, pyridyl and pyrimidinyl groups.
• Y represents a propylamino, cyclopentylamino, cyclohexylamino, phenylamino, fluorophenylamino, chlorophenylamino, bromophenylamino, iodophenylamino, methoxycarbonylphenylamino, biphenylamino, benzylamino, fluorobenzylamino, bis(trifluoromethyl)-benzylamino, phenylethylamine, phenylmethoxycarbonyl methylamino, diethylamino, morpholinyl, thiomorpholinyl, morpholinosulphonyl, indolinyl, tetrahydroisoquinolinyl, phenylpiprerazinyl, fluorophenylpiperazinyl, chlorophenylpiperazinyl, methylphenylpiperazin
• Y represents a propylamino, phenylamino, bromophenylamino, iodophenylamino, biphenylamino, benzylamino, bis(trifluoromethyl)benzylamino, phenylethylamino, phenyl-methoxycarbonylmethyl amino or morpholinyl group are especially preferred.
• the parasite is an organism of the genus Neospora or the genus Eimeria.
• the present invention also provides the use of a compound of the general formula I as defined above for the manufacture of a medicament for the treatment and/or prophylaxis of a disease caused by infection as with a parasite other than an organism of the genus Plasmodium .
• the parasite is an organism of the genus Neospora or the genus Eimeria.
• Certain compounds of the general formula I are novel and the invention therefore further provides a compound of the general formula I as defined above, with the proviso that, when Y is a group —NR 1 R 2 and R 2 represents a phenyl, 3-chlorophenyl, 4-chlorophenyl, 3-bromophenyl, 4-bromophenyl, 4-iodophenyl, 4-methylphenyl, 4-methoxyphenyl, 3-carboxylphenyl or 4-carboxylphenyl group, then R 1 is an optionally substituted alkyl group.
• the present invention also provides a process for the preparation of a novel compound of the general formula I as defined in the ante-preceding paragraph which comprises reacting a compound of the general formula II in which Q represents a hydrogen atom or trimethylsilyl group, with a suitable halogenating agent to form a compound of the general formula I in which Y represents a halogen atom; and, if desired, reacting the compound of general formula I thus formed either with a Grignard reagent of the general formula YMgX where Y is an optionally substituted cycloalkyl, aryl, C-linked heteroaryl or heterocyclylalkyl group and X is a halogen atom to form a compound of general formula I in which Y represents an optionally substituted cycloalkyl aryl, C-linked heteroaryl or heterocyclylalkyl group or with an amine of the general formula HNR 1 R 2 where R 1 and R 2 are as defined above to form a compound of general formula I in which
• Suitable halogenating agents for forming compounds of the general formula I in which Y represents a halogen atom include diethylaminosulphur trifluoride, chlorotrimethylsilane, bromotrimethylsilane and iodotrimethylsilane.
• compounds of the general formula I in which Y represents a chlorine, bromine or iodine atom may be prepared by reacting a compound of the general formula II in which Q represents a trimethylsilyl croup with a suitable chlorinating, brominating or iodinating agent respectively, such as chlorotrimethlysilane, bromotrimethylsilane or iodotrimethylsilane respectively.
• This reaction may be conveniently carried out in the presence of a solvent.
• suitable solvents include halogenated hydrocarbons, especially chlorinated hydrocarbons, such as dichloromethane.
• the reaction is carried out at a temperature of ⁇ 30° C. to +10°, particularly ⁇ 5° C. to +5° C., about 0° C. being especially preferred.
• Compounds of the general formula I in which Y represents a fluorine atom may be conveniently prepared by reacting a compound of the general formula II in which Q represents a hydrogen atom with a suitable fluorinating agent, such as diethylaminosulphur trifluoride.
• a suitable fluorinating agent such as diethylaminosulphur trifluoride.
• This reaction may be conveniently carried out in the presence of a solvent, suitable solvents including halogenated hydrocarbons, especially chlorinated hydrocarbons, such as dichloromethane.
• the reaction is carried out at ⁇ 5° C. to room temperature, that is, ⁇ 5 to +35° C., preferably 0 to 30° C.
• the reaction may also be carried out under an inert atmosphere, such as nitrogen.
• Suitable Grignard reagents for forming compounds of the general formula I in which Y is an optionally substituted cycloalkyl, aryl, C-linked heteroaryl or heterocyclylalkyl group include compounds of the general formula YMgX where X represents a chlorine, bromine or iodine atom. However, it is particularly preferred that X represents a bromine atom.
• the reaction of a compound of the general formula I in which Y represents a halogen, preferably a bromine, atom with a Grignard reagent may be conveniently carried out in the presence of a solvent.
• Suitable solvents include ethers, such as diethyl ether.
• the reaction is carried out under an inert atmosphere, such as nitrogen, at a temperature of ⁇ 5° C. to +5° C., being especially preferred. This method produces a single pure isomer of the final product.
• reaction of an amine which a compound of the general formula I in which Y represents a halogen, preferably a bromine, atom to form a compound of the general formula I in which Y represents a group —NR 1 R 2 where R 1 and R 2 are as defined above may be conveniently carried out in the presence of a solvent.
• Suitable solvents include halogenated hydrocarbons, especially chlorinated hydrocarbons, such as dichloromethane, and ethers, such as tetrahydrofuran.
• the reaction is carried out at a temperature of ⁇ 5° C. to +5° C., being especially preferred.
• a compound of the general formula II in which Q represents a trimethylsilyl group may be prepared by reacting dihydroartemisinin, that is, the compound of general formula II in which Q represents a hydrogen atom, with chlorotrimethylsilane in the presence of a base, such as pyridine or triethylamine.
• a base such as pyridine or triethylamine.
• the reaction is carried out at room temperature, that is, 15 to 35° C., preferably 20 to 30° C.
• Dihydroartemisinin that is, the compound of general formula II in which Q represents a hydrogen atom, is a known compound and can be prepared by known processes.
• Compounds of the general formula I in which Y represents an optionally substituted cycloalkyl, aryl, C-linked heteroaryl or heterocyclylalkyl group can also be prepared by reacting 9,10-anhydroartemisinin with a compound of the general formula Y—H, where Y is as defined above, in the presence of a suitable Lewis acid. This method produces a mixture of isomers in the final product.
• Suitable Lewis acids include boron trifluoride dietherate and trifluoromethanesulphonic acid.
• the reaction may be conveniently carried out in the presence of a solvent.
• Suitable solvents include halogenated hydrocarbons, especially chlorinated hydrocarbons, such as dichloromethane.
• the reaction is carried out under an inert atmosphere, such as nitrogen, at room temperature, that is, 15 to 35° C., preferably 20 to 30° C.
• 9,10-Anhydroartemisinin may be conveniently prepared by reacting dihydroartemisinin with trifluoroacetic anhydride.
• the reaction may be conveniently carried out in the presence of a solvent, preferably a halogenated hydrocarbon, and especially a chlorinated hydrocarbon, such as dichloromethane.
• a base such as pyridine or a derivative thereof, for example, dimethylaminopyridine.
• the reaction is carried out under an inert atmosphere, such as nitrogen, at a temperature of ⁇ 5° C. to +5° C., preferably 0° C., with the reaction mixture being subsequently allowed to warm to room temperature, that is, 15 to 35° C., preferably 20 to 30° C.
• Compounds of the general formula I in which Y represents an optionally substituted aryl or C-linked heteroaryl group can also be prepared by reacting 10-trichloroacetimidoyl-10-deoxoartemisinin with a compound of the general formula Y—H, where Y is as defined above, in the presence of a suitable Lewis acid, such as boron trifluoride diethyl etherate.
• a suitable Lewis acid such as boron trifluoride diethyl etherate.
• the 10-trichloroacetimidoyl-10-deoxoartemisinin is generated in situ by reacting a compound of the general formula II in which Q represents a hydrogen atom with trichloroacetonitrile in the presence of a suitable base, such as 1,8-diazabicyclo[5.4.0]undecane.
• a suitable base such as 1,8-diazabicyclo[5.4.0]undecanecane.
• the reaction to form 10-trichloroacetimidoyl-10-deoxoartemisinin is carried out at room temperature, that is, 15 to 35° C., preferably 20 to 30° C.
• the reaction may be conveniently carried out in the presence of a solvent.
• Suitable solvents include halogenated hydrocarbons, especially chlorinated hydrocarbons, such as dichloromethane.
• the remainder of the reaction is carried out under an inert atmosphere, such as nitrogen.
• the remainder of the reaction is carried out at a temperature of ⁇ 60 to ⁇ 20° C., particularly ⁇ 55 to ⁇ 30° C., and especially ⁇ 40 to ⁇ 50° C.
• Compounds of the general formula I in which Y represents an optionally substituted aryl or C-linked heteroaryl group can also be prepared by reacting a 10-acyloxyartemisinin compound in which the acyloxy group is of formula A(C ⁇ O)—O—, where A represents an optionally substituted alkyl, cycloalkyl, aryl, aralkyl, heterocyclic or polycyclic group, with a compound of the general formula Y—H, where Y is as defined above, in the presence of a suitable Lewis acid.
• Suitable Lewis acids include boron trifluoride diethyl etherate, tin(IV) chloride, copper(II)-trifluoromethanesulfonate and trifluoromethanesulphonic acid. It is preferred that the Lewis acid is boron trifluoride diethyl etherate.
• A represents an optionally substituted alkyl group, unless otherwise specified, this may be linear or branched and may contain up to 12, preferably up to 6, and especially up to 4 carbon atoms.
• Preferred alkyl groups are methyl, ethyl, propyl and butyl.
• A represents an optionally substituted aryl group
• this may be any aromatic hydrocarbon group and may contain from 6 to 24, preferably 6 to 18, more preferably 6 to 16, and especially 6 to 14, carbon atoms.
• Preferred aryl groups include phenyl, naphthyl, anthryl, phenanthryl and pyryl groups, especially phenyl, naphthyl and anthryl groups.
• an aryl moiety forms part of another group, for example the aryl moiety of an aralkyl group, it is preferred that it is a phenyl, naphthyl, anthryl, phenanthryl or pyryl, especially a phenyl or naphthyl, and particularly a phenyl, moiety.
• A represents an optionally substituted aralkyl group
• this may be any alkyl group substituted by an aryl group.
• a preferred aralkyl group contains from 7 to 30, particularly 7 to 24, more particularly 7 to 18, and especially 7 to 10, carbon atoms, particularly preferred aralkyl groups being benzyl, naphthylmethyl, anthrylmethyl, phenanthrylmethyl and pyrylmethyl groups, a benzyl group being especially preferred.
• A represents an optionally substituted cycloalkyl group
• this may be any saturated or partially unsaturated cyclic hydrocarbon group and may contain from 3 to 12, preferably 3 to 8, and especially 3 to 6, carbon atoms.
• Preferred cycloalkyl groups are cyclopropyl, cyclopentyl and cyclohexyl groups.
• A represents an optionally substituted polycyclic group
• this may be any saturated or partially unsaturated hydrocarbon group which contains more than one ring system.
• Such ring systems may be “fused”, that is, adjacent rings have two adjacent carbon atoms in common, “bridged”, that is, the rings are defined by at least two common carbon atoms (bridgeheads) and at least three acyclic chains (bridges) connecting the common carbon atoms, or “spiro” compounds, that is, adjacent rings are linked by a single common carbon atom.
• a polycyclic group may contain more than one of these types of ring system.
• Polycyclic groups preferably contain from 4 to 30, particularly 4 to 26, and especially 6 to 18, carbon atoms.
• Bicyclic, tricyclic and tetracyclic groups are particularly preferred.
• Preferred bicyclic groups contain from 4 to 14, especially 6 to 10, carbon atoms.
• Preferred tricyclic groups contain from 5 to 20, especially 6 to 14, carbon atoms with anthraquinone groups being especially preferred.
• Preferred tetracyclic groups contain from 6 to 26, especially 6 to 18, carbon atoms.
• Optional substituents for the substituent A may be any of those previously identified as suitable in this respect.
• the reaction may be conveniently carried cut in the presence of a solvent.
• Suitable solvents include halogenated hydrocarbons, especially chlorinated hydrocarbons, such as dichloromethane.
• the reaction is carried out under an inert atmosphere, such as nitrogen.
• the reaction is carried out at a temperature of ⁇ 60 to ⁇ 20° C., particularly ⁇ 55 to ⁇ 30° C., and especially ⁇ 40 to ⁇ 50° C.
• Compounds of formula I in which Y represents a substituted aryl group where at least one of the substituents is a hydroxyl group can also be prepared by rearrangement of the corresponding C-10 ether linked artemisinin derivative so that the oxygen atom of the ether link becomes the oxygen atom of the hydroxyl group in the substituted aryl group of the desired product.
• Such a rearrangement can be effected by reacting the corresponding C-10 ether linked artemisinin derivative with a Lewis acid, such as a boron trifluoride dietherate. The reaction is conveniently carried out in the presence of a solvent such as dichloromethane at a temperature of ⁇ 5° C. to +5° C., preferably 0° C.
• Certain compounds of the general formula I may also be prepared by conversion of another compound of general formula I.
• 10-(4-vinylphenyl)-dihydroartemisinin may be converted to 10-(4-carboxyphenyl)dihydroartemisinin by reaction with an oxidising agent, such as potassium permanganate.
• compounds of general formula I which contain a heterocyclic moiety having at least one sulphur atom in the ring system may be oxidised to form compounds of general formula I in which the or each sulphur atom has been converted to a sulphinyl or sulphonyl group by reaction with a suitable oxidising agent.
• Suitable oxidising agents include 4-methylmorpholine N-oxide (NMO), tetrapropylammonium perruthenate (TPAP) and mixtures thereof.
• NMO 4-methylmorpholine N-oxide
• TPAP tetrapropylammonium perruthenate
• the reaction may be conveniently carried out in the presence of a solvent, suitable solvents including halogenated hydrocarbons, especially chlorinated hydrocarbons, such as dichloromethane.
• the reaction is carried out at room temperature, that is, 15 to 35° C., preferably 20 to 30° C.
• the reaction may also be carried out under an inert atmosphere, such as nitrogen.
• the invention also provides a pharmaceutical composition which comprises a carrier and, as active ingredient, a novel compound of the general formula I as defined above.
• a pharmaceutically acceptable carrier may be any material with which the active ingredient is formulated to facilitate administration.
• a carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to form a liquid, and any of the carriers normally used in formulating pharmaceutical compositions may be used.
• compositions according to the invention contain 0.5 to 95% by weight of active ingredient.
• the compounds of general formula I can be formulated as, for example, tablets, capsules, suppositories or solutions. These formulations can be produced by known methods using conventional solid carriers such as, for example, lactose, starch or talcum or liquid carriers such as, for example, water, fatty oils or liquid paraffins.
• solid carriers such as, for example, lactose, starch or talcum
• liquid carriers such as, for example, water, fatty oils or liquid paraffins.
• Other carriers which may be used include materials derived from animal or vegetable proteins, such as the gelatins, dextrins and soy, wheat and psyllium seed proteins; gums such as acacia, guar, agar, and xanthan; polysaccharides; alginates; carboxymethylcelluloses; carrageenans; dextrans; pectins; synthetic polymers such as polyvinylpyrrolidone; polypeptide/protein or polysaccharide complexes such as gelatin-acacia complexes; sugars such as mannitol, dextrose, galactose and trehalose; cyclic sugars such as cyclodextrin; inorganic salts such as sodium phosphate, sodium chloride and aluminium silicates; and amino acids having from 2 to 12 carbon atoms such as a glycine, L-alanine, L-aspartic acid, L-glutamic acid, L-hydroxyproline, L-isoleucine,
• Suitable colouring agents include red, black and yellow iron oxides and FD & C dyes such as FD & C blue No. 2 and FD & C red No. 40 available from Ellis & Everard.
• Suitable flavouring agents include mint, raspberry, liquorice, orange, lemon, grapefruit, caramel, vanilla, cherry and grape flavours and combinations of these.
• Suitable pH modifiers include citric acid, tartaric acid, phosphoric acid, hydrochloric acid and maleic acid.
• Suitable sweeteners include aspartame, acesulfame K and thaumatin.
• Suitable taste-masking agents include sodium bicarbonate, ion-exchange resins; cyclodextrin inclusion compounds, adsorbates or microencapsulated actives.
• 0.1 to 100 ppm, preferably 0.5 to 100 ppm of the active compound may be mixed into an appropriate, edible material, such as nutritious food. If desired, the amounts applied can be increased, especially if the active compound is well tolerated by the recipient. Accordingly, the active compound can be applied with the drinking water.
• amounts of 0.5 to 100 mg/kg body weight active compound are preferably administered daily to obtain the desired results. Nevertheless, it may be necessary from time to time to depart from the amounts mentioned above, depending on the body weight of the experimental animal, the method of application, the animal species and its individual reaction to the drug or the kind of formulation or the time or interval in which the drug is applied. In special cases, it may be sufficient to use less than the minimum amount given above, whilst in other cases the maximum dose may have to be exceeded. For a larger dose, it may be advisable to divide the dose into several smaller single doses.
• the invention also includes a novel compound of the general formula I as defined above for use in the treatment and/or prophylaxis of a disease caused by infection with a parasite of the genus Plasmodium and use of a novel compound of the general formula I as defined above for the manufacture of a medicament for the treatment and/or prophylaxis of a disease caused by infection with a parasite of the genus Plasmodium .
• Preferred compounds in this respect include compounds of the general formula I in which Y represents a fluorine atom, Y represents a phenyl, dimethoxyphenyl or trimethoxyphenyl group or Y represents a propylamino, fluorophenylamino, biphenylamino, benzylamino, phenylethylamino, phenylmethoxycarbonylmethylamino or diethylamino group.
• the invention also provides a method for treating a disease caused by infection with a parasite other than an organism of the genus Plasmodium which comprises administering to a host in need of such treatment a therapeutically effective amount of a compound of the general formula I as first defined above.
• the parasite is an organism of the genus Neospora or the genus Eimreria .
• a method for treating a disease caused by infection with a parasite of the genus Plasmodium is also provided which comprises administering to a host in need of such treatment a therapeutically effective amount of a novel compound of the general formula I as defined above.
• the parasiticidal activity of compounds of the invention was investigated by means of the following tests.
• RPMI medium 100 ml, 95% RPMI 1640, 2% FCS, 1% L-glutamine, 1% sodium hydrogen carbonate, 1% penicillin/streptomycin.
• the cell suspension was pipetted into six 96-well plates at 150 ⁇ l per well.
• the coated cell culture plates were placed in an incubation cupboard at 37° C. under 5% CO 2 for 24 hours.
• the cells were then infected with Neospora caninum tachyzoites at a concentration of 48,000 tachyzoites per well. This was followed by incubation at 37° C. under 5% CO 2 for 24 hours.
• test compounds (0.5-1.5 mg) were weighed into 1.5 ml eppendorf vessels and dissolved in 1 ml dimethyl sulphoxide, corresponding to a dilution of about 1 ⁇ 10 ⁇ 3 g ml ⁇ 1 .
• the medium used for further dilution consisted of 87% RPMI 1640, 10% FCS, 1% L-glutamine, 1% sodium hydrogen carbonate, 1% penicillin/streptomycin.
• concentrations of 10 ⁇ 5 , 10 ⁇ 5 and 10 ⁇ 7 g ml ⁇ 1 were used.
• the diluted preparations were then transferred to the cell culture plates at a volume of 150 ⁇ l per well after 24 hour infection with Neospora caninum .
• untreated medium was used; this row contained infected and uninfected cells as controls.
• the cell plate was incubated at 37° C. under 5% CO 2 for 5 days.
• Microscopic evaluation was conducted 4 days after treatment and 5 days after infection at a magnification of 25 ⁇ 10 in an inverse microscope according to the following evaluation scheme.
• the assay relies on incorporation of radiolabelled hypoxanthine by the parasite and inhibition of incorporation is attributed to activity of known or candidate antimalarial drugs.
• proven antimalarials such as chloroquine, mefloquine, quinine, artemisinin and pyrimethamine were used as controls.
• the incubation period was 66 hours, and the starting parasitemia was 0.2% with 1% hematocrit.
• the medium was an RPMI-1640 culture with no folate or p-aminobenzoic acid.
• Albumax rather than 10% normal heat inactivated human plasma was used as, with Albumax, less protein binding is observed, and compounds elicit slightly higher activities in this model.
• DMSO dimethyl sulphoxide
• a prescreen format can be used wherein a 3-dilution assay may be used to determine activity at high medium or low concentrations.
• concentrations were selected as 50,000, 500 and 50 ng ml ⁇ 1 . These were performed in duplicate on a 96-well format plate with 14 test compounds and one known (standard) compound per plate. The system was automated with a Biomek diluter for mixing and diluting the drugs, and adding drugs and parasites to a test plate.
• the ANALYSIS FIELD AP
• the compound was “very active” and the IC values are most likely to be below the last dilution value (in nanograms/ml), which is listed next to AF.

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